Photographic duplicating process



Patented Mar. 9, 1937 Geza Szasz,'Berlin, Germany No Drawing.Application July is, 1935, Serial No. 31,609. In Germany February 21,1935 .5 Claims.

This invention relates to a photographic procress for duplicatingprinted matter, maps and other documentary representations havingstrongly contrasting lines, the process being characterized by afaithful reproduction of the original and the facility or rapidity withwhich it can be carried out. The invention also includes an improvedgelatin matrix for use in the process.

In carrying out the process of the invention, a washed out relief matrixis photographically produced in a silver halide gelatin emulsion layercarried by a suitable flexibletransparent base. This silver halidegelatin emulsion layer should 15 be one capable of reproducing strongcontrasts.

In general, the relief matrix is formed by selectively exposing thelight sensitized gelatin layer in accordance with an originalrepresentation, and properly developing and treating the selectivelyexposed layer. This may be accomplished by exposing the gelatin layer tolight passed through a photographic negative of the originalrepresentation, and then developing the gelatin layer with pyrocateoholdeveloper-free from sulphite or with a similar developer capable oftanning the gelatin layer in proportion to the exposure thereof. Theunexposed and untanned gelatin isthen washed out with warm water and atrue image of the original, in the form of a washed out relief, istherebyobtained. The making of the negative from which the matrix isformed may be accomplished photographically, by a reflex copying processor by contact printing.

In accordance with the invention, I prefer to slightly color the silverhalide gelatin layer forming the matrix with a suitable substance, as bythis means I can accurately control the formation of the washed outrelief to a remarkable de- 40 gree. The coloring of the gelatin layerrenders it visible and accordingly, the operator can readily determinewhen all of the unexposed gelatin has been washed away. In this manner,a

matrix comprising a highly accurate and faithful image of the originalis obtained.

The coloring substance so employed should be of such a nature that itdoes not react with the water soluble dyes which may be subsequentlyused in printing, and I have found that pigments 50 may be employed forthis purpose. The pigment may be incorporated in the silver halidegelatin layer by mixing it in the emulsion from which this layer isprepared.

The duplicating process may be carried out ac- 55 cording to twodifferent methods of procedure.

(Cl. ll-31.5)

According to one embodiment of the invention, the washed out reliefmatrix, produced as described above, is colored with water solublecopying dye of high tinctorial power, such as methylene blue ormethylene violet. Such dyes are commonly used in the known hectographicinks. This can be done by the dusting process in which the matrix ismoistened, then blotted to remove moisture from the areas not covered bythe gelatin layer and then dusted with the dye in powdered form, theexcess dry dye being shaken off. The dye adheres to the gelatin coatedportions of the matrix which have retained some moisture, but does notadhere to the dry exposed base on which the gelatin is carried. As analternative to the dusting process of dye application, I may employ adye layer formed of a highly concentrated water soluble dye providedwith a binder and if necessary with wetting additions. This dye layermay be formed by coating on a backing of paper or the like, a mixturecomprising a dye of high tinctorial power, ,such as methylene blue ormethylene violet, a binder, such as japan wax, and a moistening agent,such as glycerin.

The dye layer is pressed on to the matrix, the relief image portions ofwhich have been previously moistened, andthe dye is thereby transferredto the relief image.

The dye image, produced either by the dusting process or the dye layerprocedure jdescribed 'above, is then transferred to a second layer ofgelatin or similar material having glycerin in-. corporated therein tokeep it moist, this being accomplished by-squeezing the matrix againstthe second layer. This forms on the second'layer printing areas coveredwith dye. The second gelatin layer forms a printing matrix from whichimpressions can be made on paper or other material in considerablenumbers.

I claim:

1. A process of duplicating printed matter and other documents havingstrongly contrasting lines, comprising forming a matrix carrying awashed out relief image-by selectively exposing a light sensitizedsilver halide gelatin layer in accordance with an originalrepresentation, said layer being carried on a flexible imperforatesupport and being capable of reproducing strong contrasts, tanning theexposed portions of said layer with a developer and washing out theunexposed portions thereof, applying a water soluble dye of hightinctorial power to the relief image of said layer to transfer the dyeimage thereto and makmatrix, pressing said matrix on a second gelatining impressions from the dye image on said second gelatin layer. 2. Aprocess of duplicating printed matter and other documents havingstrongly contrasting lines, comprising forming a matrix carrying awashed out relief image by selectively exposing a colored lightsensitized silver halide gelatin layer in accordance with an originalrepresentation, said layer being carried on a flexible imperforatesupport and being capable of reproducing strong contrasts, tanning theexposed portions of said layer with a developer and washing out theunexposed portions thereof, applying a water soluble dye of hightinctorial' power to the relief image of said matrix, pressing saidmatrix on a second gelatin layer to transfer'the dye image thereto andmaking impressions from the dye image on said second gelatin layer.

3. A process of duplicating printed matter and other documents havingstrongly contrasting lines, comprising forming a matrix carrying awashed out relief image by selectively exposing a light sensitizedsilver halide gelatin layer in accordance with an originalrepresentation, said layer being carried on a flexible imperforatesupport and being capable of reproducing strong contrasts, tanning theexposed portions of said layer with a developer and washing out theunexposed portions thereof, moistening the-relief image of the matrix,applying to the moistened relief image a dye of high tinctorial power inpowdered form, pressing the matrix on a second gelatin layer to transferthe dye image thereto and making impressions from the dye image on saidsecond gelatin layer.

4. A process of duplicating printed matter and other documents havingstrongly contrasting lines, comprising forming a matrix carrying awashed out relief image by selectively exposing a light sensitizedsilver halide gelatin layer in accordance with an originalrepresentation, said layer being carriedon a flexible imperforatesupport and being capable of reproducingstrong contrasts, tanning theexposed portions of said layer with a developer and washing out theunexposed portions thereof, pressing a dye layer comprising a watersoluble dye of high tinctorial power mixed with a binder and amoistening agent against the relief image of said matrix whereby the dyeis applied to the relief image, pressing the matrix on a second gelatinlayer to transfer the dye image thereto and making impressions from thedye image on said second gelatin layer.

5. A process of duplicating printed matter and other documents havingstrongly contrasting lines, comprising preparing a negative of theoriginal document, exposing a silver halide gelatin photographicemulsion layer carried on a flexible imperforate support and capable ofreproducing strong contrasts to light through said negative, tanning theexposed portions of said layer with a developer and washing out theunexposed portions thereof, thereby forming a matrix constituting apositive washed out gelatin relief image of said original document onsaid support, moistening said gelatin relief, applying a hectographicink thereto, transferring said ink from said relief to a hectographicgelatin printing layer, and making copies from the dye image on saidhectographic layer.

GEZA SZASZ.

